Gas turbine plant



May 20, 1941. w. TRAUPEL 2,242,767

GAS TURBINE PLANT Filed April 5, 19:59 2 Sheets-Sheet 1 3a 3% 3C 5: /6' 2/ I 2 23b 7 I If 011 w fy 22 r 1417 20 23 p INVENTOR 146 14 ATTORNEYS May 20, 1941. WAUPEL 2,242,767

GAS TURBINE PLANT Filed April 5, 1939 2 Sheets-Sheet 2 ATTORNEY Patented May 20, 1941 GAS TURBINE PLANT l Walter Traupel, Winterthur, Switzerland, as-

signor to Sulzer Freres, Winterthur, Switzerland Socit Anonyme,

Application April 5, 1939, Serial No. 266,229 In Switzerland April 7, 1938 6 Claims.

The invention refers to a gas turbine plant in which the air used for combustion is compressed by a multi-stage compressor and the power gas is expanded in a multi-stage gas turbine with intermediate heating between separate stages. The invention consists in that only a part of the gas flowing from one stage of the turbine to the next is taken from the turbine and heated in an'intermediate reheater with the help of a burner and then mixed with the gas not taken from the turbine, in order to allow the combustion in the intermediate reheater to take place at as high a temperature as possible while using a small amount of excess air. The reheated power gas can be led by means of inlet devices into the centre of guide passage cross-sections, where it is mixed with the non re-heated gas. The quantity of power gas taken from the turbine is pref-'- erably led through a diffuser into the intermediate reheater.

It may be advantageous to arrange the passages for leading the gas to the intermediate reheater and the passages for leading the gas back from the intermediate reheater at least approximately circularly symmetrical with regard to the turbine axis. Preferably the gas will be given a swirl before entering the intermediate reheater. Also some of the passages in a guide piece may have hotter gas flowing through them than the other passages in the guide piece. In this case preferably the conducting passages for the hotter gas and the conducting passages for the cooler gas have diflerent cross-sections. For example, a guide passage for the hotter gas and a guide passage for the cooler gas may follow each other alternately. It is also preferable to choose the cross-sections of fiow in the intermediate reheater and in the passages for the hotter gas in such a way that a pressure drop occurs which gives at the outlet of the guide passages for the hotter gas approximately the same speeds as the cooler gas has at the outlet of the guide passages. If slits are provided at the entrance to the passages conducting the hotter gases, '9. part of the colder gas can enter the passage containing the hotter gases in order to form a cooling boundary layer along the surfaces of the guide blades.

Two examples illustrating the object of the invention'are given more or less diagrammatically in the accompanying drawings.

Fig. 1 shows a longitudinal section through the whole group of machines;

Fig. 2 is an enlarged'fragmentary longitudinal view along the line 2--2 of Fig. 3;

Fig. 3 is a sectional view along the line 3-4 of Fig.2;

Fig. 4 is an entropy diagram showing the change of state of the gases in the turbine of Fig. 1;

Fig. 5 is a longitudinal sectional view through a modified turbine embodying the invention taken along the line 5--5 of Fig. 6;

Fig. 6 is a fragmentary cross sectional view along the line 6-6 of Fig. 5;

Fig. '1 is a. view along the line 1-1 of Fig. 5;

Fig. 8 is an entropy diagram showing the thermal changes taking place in the machine according to Figs. 5 and 6, and

Fig. 9 is an enlarged fragmentary view along the line 9-9 of Fig. 6.

The gas turbine plant according to Fig. 1 comprises a multi-stage compressor I, which compresses the air required for combustion, and a multi-stage gas turbine 2, with several intermediate reheaters 3a, 3b and 30, which heat the gases during their expansion between separate stages of the turbine.

The compressor i draws the air required for combustion through the branch 4 and compresses it in a first stage 5. The air then passes into the first intermediate cooler Ba, is compressed further in another stage 1, again cooled in a further intermediate cooler 6b, and compressed to the final pressure in the last stage 8. The compressed air flows from the compressor through the pipe 9 into the heat exchanger l0, and from this through pipe ll into the combustion chamber l2.

Through the burner l3 a power gas with a temperature of about 500-600" C. is produced, which passes first of all into a first turbine stage ll. At the end of this stage a part of the power gases goes through the passage l5 and through a diffuser |5a into the combustion chamber of the intermediate reheater 3a. The other part of the gases flows through the passage l6 direct to stage II. On entering stage I! this latter part of the power gas mixes again with the first part of the power gas from the intermediate heater, in such a way that the temperature again becomes about 500-600 C. At the outlet of stage I! the gases are again divided into two parts, which go through the passages I8 and i9 respectively. The part flowing through the passage I8 is heated in the intermediate reheater 3b and mixed again with the part flowing through the passage l9, so that at the inlet to stage 20 the temperature again becomes about 500-600 C. A similar subdivision between passages 2| and 22,

and intermediate heating in an intermediate reheater 50, takes place before entering the last stage 23. The power gases, which are still very highly heated, then flow out of the turbine through pipe 24 into the heat exchanger Hi,- and from there through pipe 25 to the atmosphere. Each of the three stages l4, I1, 20 and 23 comprises a plurality of groups of rotor blades l4a, Ila, 20a and 23a respectively mounted on the rotor 24a and a plurality of groups of guide blades I 4b, 11b, 20b and 2317..

Figs. 2 and 3 show the outlet of the gases from the first stage I4, the dividing of the gases into two passages I5 and I6, and their entrance into the following stage II. The gas branching ofi through passage l5 and then heated in the intermediate reheater, is distributed over the whole periphery of the turbine through a substantially annular passage 26 and led through a number of inlet passages 21 in a plurality of radially disposed hollow guide members 21a to the guide passages 21b between the guide blades in such a way that the heated power gases flow into the middle of the guide passage cross-sections as indicated by the arrows 29, while the power gases that are not re-heated flow first along the guide members 21a as indicated by the arrows 30. The gases that have been heated in the intermediate reheaters and the gases that have not been re-heated then mix in the course of flowing through the guide passages 21b and through the rotor passages 30a located between the blades Ila.

The working process represented in the entropy diagram on Fig. 4 refers to a gas turbine installation in which the compressed air is cooled in three intermediate coolers and the power gases are heated in seven intermediate heaters. The air is drawn in by the compressor in the state 0 at a pressure pi and passed from the compressor to the heat exchanger in the state A with the pressure 112. There the heat of the exhaust gases from the turbine is utilised to heat the whole quantity of air to bring it into the state B. A further heating takes place in the combustion chamber arranged before the gas turbine, until a power gas with the state C is formed. These power gases are expanded in a first group of stages to the State D. After this expansion a part of the power gases are heated in an intermediate heater and brought to the state E and then mixed with the nonheated power gases, so thatv the total quantity of power gases comes to the state F. After the intermediate heating process has been repeated another six times the gases flow through the last group of stages and then arrive, in the state H, through the exhaust piping into the heat exchanger where their heat is transferred to the air compressed by the turbine. The difierence in temperature At between the states B and H is utilised in the heat exchanger for transmitting the heat of the exhaust gases to the compressed air.

The turbine shown in Figs. 5, 6 and 7 comprises a number of stages Ma and 4H) having groups of rotor blades 42 on the rotor 4| and groups of guide blades 44 on the support 43. The whole is surrounded by the turbine casing 45.

From the first stage 4la. a part of the gases passes direct to the next stage 4Ib through a passage 46. Another part, however, flows through a passage 41 into an annular passage 48 and from there through a ring-shaped pipe 49 into an intermediate reheater 50. The intel-mediate reheater is fitted with a burner 5|,

the fuel from which is burnt with the help of' the oxygen contained in the gases. The heated gases then flow through the pipe 52 into the sub stantially annular passage 53. From this annular passage the gases then pass into the radial passages 54 formed in the spaced bailles 59.

The radial passages 54 (Fig. 7) lead to separate guide passages 55. The passages 46 open into the guide passages 56. The gases passing through the guide passages 55 are hotter than the gas passing through guide passages 56. The cross-sections of the guide passages 55 are, as can be seen, diflerent from those of the guide passages 56. Preferably the cross-sections the passages 41, 48, 49, 52, 53, 54 and 55 are of such dimensions that a certain pressure drop occurs which gives the hotter gas approximately the same speeds at the outlet of the guide passages 55, as the cooler gas has at the outlet of the guide passages 56. At the inlet of the guide passages 55, slits 51 are provided, through which a part of the colder gas can enter into the passages 55 in order to form a cooling layer along the guide blade surfaces. Both the annular passage 48 as well as the annular passage 53 are arranged approximately circularly symmetrical with respect to the axis of the turbine runner 4|. With the help of the blades 58 the gas can be given a certain swirl when entering the intermediate heater.

In the entropy diagram shown in Fig. 8 the pressure before the entrance of the gas into the passages 46 or 41 (Fig. 5) is indicated by m. 122 represents the pressure at the outlet of the guide blades 44 (Fig. '7). A part of the gases pass directly into the guide passages 56 (Fig. '1). The state of this part of the gases consequently changes from the entrance into the passage 46 (Fig. 5) to outlet from the guide blades 44 (Fig. 7) along the line AA (Fig. 8). The other part of the gases that pass through the passage 4'! to the intermediate reheater and from there into the guide passages 55 undergoes at first a change of state along the line A-B (Fig. 8). The pressure then falls from the value 121 to the value in. The point B corresponds to the state of the gas at .the inlet into the guide passage 55. In the guide passages the gas expands to the state B. From the entropy diagram it can be seen that by giving the passages a suitable shape the heat drops 71. and h for the gas in the guide passages 56 and also for the gas in the guide passages 55 respectively can be chosen the same size. The speeds occurring at the outlet from the passages 55 and at the outlet from the passages 55 will consequently also be equal.

Through the described division of the gas stream into one part that passes through the intermediate heater and into a second part that flows direct to the next group of stages, the flow losses that are connected with the intermediate heating are considerably reduced, since the kinetic energy at the outlet of that part of the gas that flows direct through is utilised again in the first stage after the intermediate heating, whilst on the other hand the flow losses in the intermediate heater affect only the highly heated part of the gas. The flow losses that are connected with the intermediate heating are thus reduced to a minimum, whilst at the same time the space required by the machine is considerably smaller, since the cross-sections of flow and the dimensions of the intermediate heater are considerably reduced.

I claim:

1. A multi-stage gas turbine which comprises a casing, a plurality of stages within the casing, the adjacent stages being arranged close to each other in the axial direction, an intermediate reheater between the adjacent stages, means for passing a part of the gas from one stage to the intermediate reheater, conduit means to conduct the gases from the reheater to the next stage, and a passage within the casing for passing another part of the gas directly to the said next stage, said passage being arranged in the axial dire tion of the turbine thereby effectively avoiding changes in direction of the gas flow.

2. A multi-stage gas turbine according to claim 1 which comprises a gas difiuser arranged between the separate stages and the reheaters.

3. A multi-stage gas turbine according to claim 1 which comprises a substantially annular passage into which the reheated gases from the reheaters are discharged, a plurality of spaced guide-members mounted along the inner side of the annular passage and between the adjacent stages, each of said guide members being provided with a passage through which the gases from the annular passage may pass to the. next stage, said guide members being so arranged that the gases passing directly from one stage to the next pass therebetween.

4. A multi-stage gas turbine which comprises alternate groups of rotor blades and groups oi guide blades in each stage, a substantially annular passage arranged between adjacent stages, means for passing a part of the expanded gases from one stage into the annular passage, means for heating the gases from the annular passage, a second substantially annular passage arranged to receive the heated gases, a plurality of spaced bafiies arranged radially between the adjacent stages forming passages for directing the heated gases from the second annular passage to the first group of guide blades of the next stage, and

passage means extending in the axial direction of the rotor for passing another part of the expanded gases from one stage directly to the next stage.

5. A a multi-stage gas turbine according to claim 4 in which the passage means extending in the axial direction of the rotor includes a plurality of passages formed between the said battles.

6. A muiti-stage gas turbine according to claim 4 in which the passages in the battles and the passage means extending in the axial direction of the rotor are arranged to discharge the heated gases and the other part of the expanded gases in the spaces between the guide blades of the said first group of guide blades.

WALTER TRAIlPEL. 

